About the book: 2007 / Katherine Fisher, author of the Oracle-Archon-Scarab trilogy, which has become a bestseller in many countries around the world, returns to the reader with a new exciting novel in the fantasy genre. Robert, the main character of “The Secret of the Underground Kingdom,” thanks to a meeting with a mysterious druid, finds himself in the land of our fantasies, where, between sleep and reality, his younger sister is already located. Overcoming a huge number of obstacles, traps and dangers, Robert tries to find the key to saving the girl..